U.S. patent application number 13/783264 was filed with the patent office on 2014-09-04 for sapphire property modification through ion implantation.
This patent application is currently assigned to Apple Inc.. The applicant listed for this patent is APPLE INC.. Invention is credited to Dale N. Memering, Christopher D. Prest, Douglas Weber.
Application Number | 20140248472 13/783264 |
Document ID | / |
Family ID | 50159037 |
Filed Date | 2014-09-04 |
United States Patent
Application |
20140248472 |
Kind Code |
A1 |
Memering; Dale N. ; et
al. |
September 4, 2014 |
SAPPHIRE PROPERTY MODIFICATION THROUGH ION IMPLANTATION
Abstract
Systems and methods for strengthening a sapphire part are
described herein. One method may take the form of orienting a first
surface of a sapphire member relative to an ion implantation
device, selecting an ion implantation concentration and directing
ions at the first surface of the sapphire member. The ions are
embedded under the first surface to create compressive stress in
the sapphire surface.
Inventors: |
Memering; Dale N.; (San
Francisco, CA) ; Prest; Christopher D.; (San
Francisco, CA) ; Weber; Douglas; (Arcadia,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
APPLE INC. |
Cupertino |
CA |
US |
|
|
Assignee: |
Apple Inc.
Cupertino
CA
|
Family ID: |
50159037 |
Appl. No.: |
13/783264 |
Filed: |
March 2, 2013 |
Current U.S.
Class: |
428/192 ;
118/620; 118/723R; 427/523; 501/41 |
Current CPC
Class: |
C30B 29/20 20130101;
Y10T 428/24777 20150115; H01J 2237/20207 20130101; H01J 2237/202
20130101; C30B 31/22 20130101; H01J 2237/31701 20130101; H01J
37/32412 20130101; C23C 14/48 20130101; C03C 21/007 20130101 |
Class at
Publication: |
428/192 ;
427/523; 118/620; 118/723.R; 501/41 |
International
Class: |
C23C 14/48 20060101
C23C014/48; C03C 21/00 20060101 C03C021/00 |
Claims
1. A method comprising: orienting a first surface of a sapphire
member relative to an ion implantation device; selecting an ion
implantation concentration; and directing high energy ions at the
first surface of the sapphire member, the high energy ions
embedding under the first surface to create a compressive stress in
the sapphire surface.
2. The method of claim 1, wherein the high energy ions are directed
at the first surface to achieve an ion concentration of
approximately between 10.sup.13 and 10.sup.19 ions/cm.sup.2.
3. The method of claim 2, wherein the high energy ions are
implanted with a concentration gradient across the first
surface.
4. The method of claim 2, wherein the first surface comprises at
least two zones, each having a different implanted ion
concentration.
5. The method of claim 4, wherein a first zone of the at least two
zones comprises a peripheral edge of the first surface and a second
zone of the at least two zones comprises a center portion of the
first surface.
6. The method of claim 1 further comprising: reorienting the
sapphire member; selecting an ion implantation concentration; and
directing ions at a secondary surface of the sapphire member, the
ions embedding under the secondary surface to create a compressive
stress in the secondary surface.
7. The method of claim 6, wherein the selected ion implantation
concentration under the secondary surface is different from a
corresponding ion implantation concentration under the first
surface.
8. The method of claim 1, wherein the high energy ions directed at
the first surface and the ions directed at the secondary surface
are each selected to comprise one or more of nitrogen ions, argon
ions, titanium ions, or iron ions.
9. The method of claim 8, wherein the selected ions comprise +1
ions.
10. The method of claim 8, wherein the selected ions comprise +2
ions.
11. The method of claim 1, wherein the high energy ions penetrate
to and are embedded in a primary lattice layer of the sapphire
member.
12. The method of claim 1, wherein the high energy ions penetrate
to and are embedded in a secondary lattice layer of the sapphire
member.
13. The method of claim 1 further comprising masking a portion of
the sapphire surface to preclude ion implantation in the masked
portion of the sapphire surface.
14. A system for ion implantation, the system comprising: an ion
source configured to receive an element; an ion extraction unit
coupled to the ion source for creating an ion stream; a redirecting
magnet sequentially following the ion extraction unit along the ion
stream; a mass analyzing slit that filters the redirected ion
stream; an ion acceleration column that accelerates the filtered
ion stream; a plurality of lenses that focus the ion stream; a
scanning unit that directs the ion stream into an end station; and
a support member in the end station for supporting and manipulating
a position of a sapphire part with respect to the ion stream, such
that the ions are implanted beneath a selected surface thereof.
15. The system of claim 14, wherein the support member is rotatable
to expose at least two sides of the sapphire part to the ion
stream.
16. The system of claim 14, wherein the ion source is configured to
receive at least one of elemental nitrogen, titanium, iron and
argon for extraction by the ion extraction unit to create the ion
stream.
17. A method comprising: forming a sapphire component for an
electronic device; embedding selected ions into a selected surface
of the sapphire component, wherein the selected ions are embedded
at a target depth beneath the selected surface; heating the
sapphire component to a sufficient temperature such that the
selected ions diffuse to a greater depth than the target depth
beneath the selected surface of the sapphire component, in a
concentration sufficient to generate compressive stress
therein.
18. The method of claim 17 further comprising: immersing the
sapphire component in a plasma comprising the selected ions, such
that the selected surface is exposed; and applying a voltage to the
sapphire component, such that the selected ions are embedded into
the sapphire component at the target depth beneath the selected
surface.
19. The method of claim 18 further comprising embedding additional
ions into the selected surface after heating the sapphire component
to diffuse the selected ions to greater depth.
20. The method of claim 19, wherein the additional ions are
embedded at a different target depth than that of the selected ions
embedded before heating the sapphire component.
21. The method of claim 19, wherein the additional ions are
generated from a different element than that of the selected ions
embedded before heating the sapphire component.
22. The method of claim 17 further comprising masking the sapphire
component such that the selected surface is exposed to the selected
ions, wherein at least one other surface of the sapphire component
is masked such that the selected ions are not embedded therein.
23. A mobile device comprising a sapphire cover glass component
formed according to the method of claim 17.
24. An apparatus for performing the method of claim 17, the
apparatus comprising: a plasma source configured to generate a
plasma comprising the selected ions; a vacuum chamber for immersing
the sapphire component in the plasma, such that the selected
surface is exposed to the selected ions; an electrode in charge
communication with the sapphire component for applying a voltage
thereto; and a power supply for generating the voltage on the
electrode, such that the selected ions are embedded into the
sapphire component at the target depth beneath the selected
surface.
25. The apparatus of claim 24, wherein the power supply is
configured to generate the voltage with a gradient across the
electrode, such that the ions are embedded into the selected
surface of the sapphire component at different depths or
concentrations along the gradient.
26. The apparatus of claim 24, wherein the vacuum chamber comprises
a vacuum furnace for heating the sapphire component to diffuse the
selected ions to greater depth therein.
27. The method of claim 17 further comprising: directing a beam of
the selected ions onto the selected surface of the sapphire
component; and selecting an energy for the beam, such that the
selected ions are embedded within the sapphire component at the
target depth beneath the selected surface.
28. The method of claim 17 further comprising: applying an ion
paste comprising the selected ions to the sapphire component;
electrically coupling terminals to the ion paste, wherein a
terminal is coupled to the ion paste on the selected surface of the
sapphire component; and supplying an electrical current to the
terminals, such that the selected ions are embedded within the
sapphire component, at the target depth beneath the selected
surface.
29. A method of implanting ions into a sapphire member, the method
comprising: applying an ion paste to two sides of the sapphire
member; electrically coupling terminals to the ion paste, wherein a
terminal is coupled to the ion paste on each side of the sapphire;
supplying an electrical current to the terminals; and alternating a
direction of the electrical current of the terminals.
30. The method of claim 29 further comprising: heating the sapphire
member; supplying additional electrical current to the terminals,
after heating the sapphire member; and alternating the direction of
the additional electrical current supplied to the terminals.
31. The method of claim 29, wherein the electrical current
comprises a direct current.
32. The method of claim 29, wherein the electrical current
comprises an alternating current.
33. The method of claim 29, wherein the current is supplied from
one or more capacitors.
34. A sapphire window comprising: a top surface implanted with ions
to strengthen a crystalline structure of the sapphire window; and
at least one edge surface implanted with ions, whereby the at least
one edge surface is substantially opaque to reduce cross talk into
the sapphire window.
35. The sapphire window of claim 34, wherein a concentration of the
ions implanted in the top surface of the sapphire window is
different from that of the at least one edge surface.
36. The sapphire window of claim 34, wherein different ions are
implanted in the top surface of the sapphire window and the at
least one edge surface of the sapphire window.
Description
TECHNICAL FIELD
[0001] The present application is directed to sapphire materials
and, more particularly, to the physical properties of corundum and
other processed sapphire materials.
BACKGROUND
[0002] Corundum is a crystalline form of aluminum oxide and is
found in various different colors, all of which are generally
commonly referred to as sapphire except for red corundum which is
commonly known as ruby and pinkish-orange corundum which is known
as padparadscha. Transparent forms of corundum are considered
precious stones or gems. Generally, corundum is extraordinarily
hard, with pure corundum defined to have a hardness of 9.0 on the
Mohs scale, and, as such, is capable of scratching nearly all other
minerals.
[0003] As may be appreciated, due to certain characteristics of
corundum, including its hardness and transparent characteristics,
among others, it may be useful in a variety of different
applications. However, the same characteristics that are beneficial
for particular applications commonly increase both the cost and
difficulty in processing and preparing the sapphire for those
applications. As such, beyond costs associated with it being a
precious stone, the costs of preparing the corundum for particular
uses is often prohibitive. For example, the sapphire's hardness
makes cutting and polishing the material both difficult and time
consuming when conventional processing techniques are implemented.
Further, conventional processing tools such as cutters experience
relatively rapid wear when used on corundum.
SUMMARY
[0004] Systems and methods for strengthening a sapphire part are
described herein. One method may take the form of orienting a first
surface of a sapphire member relative to an ion implantation
device, selecting an ion implantation concentration and directing
(e.g., high energy) ions at the first surface of the sapphire
member.
[0005] The ions are embedded into the sapphire member, and may
create compressive stress in the sapphire surface. For example, the
ions may be interstitially embedded under the first surface,
between existing crystal lattice sites, in order to create a
compressive stress in the sapphire surface. Alternatively, the ions
may fill vacant sites in the sapphire lattice, or the ions may be
embedded so as to make portions of the embedded region
substantially amorphous or non-crystalline in nature.
[0006] Another embodiment may take the form of a system for ion
implantation. The system may include an ion source configured to
receive an element, an ion extraction unit coupled to the ion
source that creates an ion stream, a redirecting magnet
sequentially following the ion extraction unit, and a mass
analyzing slit that filters the redirected ion stream.
Additionally, the system may include an ion acceleration column
that accelerates the filtered ion stream, a plurality of lenses for
focusing the ion stream, a scanning unit that directs the ion
stream into an end station, and a support member in the end station
for supporting and manipulating the position of a sapphire part, in
which the ions are embedded.
[0007] Plasma ion immersion may also be utilized as an ion
implantation system or process. In plasma ion immersion, available
ion energies may be somewhat lower than those achieved with ion
beam implantation, with higher throughput. For example, a plasma
ion immersion system for embedding ions into the surface of a
sapphire component may include a plasma (ion) source, a vacuum
chamber, and coupling mechanism for coupling the plasma source to
the vacuum chamber. The vacuum chamber may include a slit valve and
a turbomolecular pump or other pumping system to maintain low
pressure. A power supply (e.g., a pulsed DC power supply) may be
utilized to direct ions from the plasma source to the surface of a
sapphire component, in which the ions may be implanted as described
above.
[0008] Still other embodiments may take the form of a method of
implanting ions into a sapphire member. The method may include
applying an ion paste to two sides of the sapphire member and
electrically coupling terminals to the ion paste. A terminal (e.g.
a unique terminal) may be coupled to the ion paste on each side of
the sapphire. Additionally, the method may include supplying an
electrical current to the terminals and alternating a direction of
the electrical current of the terminals.
[0009] Further, another embodiment may take the form of a sapphire
window. The sapphire window may include a top surface implanted
with ions to help strengthen a crystalline structure of the
sapphire window. At least one edge surface of the sapphire window
may be implanted with ions to help prevent cross talk into the
sapphire window.
[0010] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following Detailed Description. As will
be realized, the embodiments are capable of modifications in
various aspects, all without departing from the spirit and scope of
the embodiments. Accordingly, the drawings and detailed description
are to be regarded as illustrative in nature and not
restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates an example sapphire part.
[0012] FIG. 2A illustrates an example ion implantation system for
implanting ions into surfaces of the sapphire part of FIG. 1.
[0013] FIG. 2B illustrates an alternate ion implantation system for
implanting ions into surfaces of the sapphire part.
[0014] FIG. 3 illustrates a support member of the ion implantation
system of FIG. 2A or 2B, for supporting the sapphire part during
the ion implantation process.
[0015] FIG. 4 is a partial cross-sectional view of the sapphire
part taken along line IV-IV of FIG. 3 and showing a lattice
crystalline structure.
[0016] FIG. 5 is a partial cross-sectional view of the sapphire
part taken along line IV-IV of FIG. 3 and showing ions implanted in
the lattice crystalline structure.
[0017] FIG. 6 is a partial cross-sectional view of the sapphire
part taken along line IV-IV of FIG. 3 and showing a compressive
layer, for example to reduce or prevent crack propagation in the
sapphire part.
[0018] FIG. 7 is a partial cross-sectional view of the sapphire
part taken along line IV-IV of FIG. 3 and showing a compressive
layer on both top and bottom surfaces of the sapphire part.
[0019] FIG. 8 is a plot illustrating the strength of the sapphire
part relative to the concentration of ions implanted in the
sapphire part.
[0020] FIG. 9 illustrates the support member of FIG. 3 holding the
sapphire part so that edges of the part may be bombarded with
ions.
[0021] FIG. 10 illustrates a chamfered edge of a sapphire part with
a curve indicating the concentration of the ions.
[0022] FIG. 11 illustrates a heating step for diffusing ions
further into the lattice crystalline structure.
[0023] FIG. 12 illustrates an ion implantation step following the
heating step of FIG. 11 to increase the concentration of ions at
the surface of the sapphire part.
[0024] FIG. 13 illustrates the sapphire part of FIG. 1 having
different zones of ion implantation to achieve a desired effect
such as colorization of a zone.
[0025] FIG. 14 is a flowchart illustrating a method of ion
implantation in accordance with an example embodiment.
[0026] FIG. 15 illustrates a system for ion implantation into a
sapphire structure in accordance with an alternative
embodiment.
[0027] FIG. 16 illustrates the system of FIG. 15 with terminals
biased for ion flow.
[0028] FIG. 17 illustrates an implantation curve showing the
compressive stress at different depths of a crystalline structure
due to ion implantation. The horizontal axis represents the depth
in the crystalline structure and the vertical axis represents the
stress level.
[0029] FIG. 18 illustrates the implantation curve of FIG. 17 with a
smoothing region between two peaks.
[0030] FIG. 19 illustrates an alternate implantation or net stress
curve.
[0031] FIG. 20 is a flowchart illustrating an ion implantation
process that includes an atom bombardment step to replace displaced
atoms of the crystalline structure.
[0032] FIG. 21 illustrates a camera window with trim to prevent
cross talk.
[0033] FIG. 22 illustrates a sapphire window with colored edges to
prevent cross talk.
DETAILED DESCRIPTION
[0034] While sapphire's inherent strength is higher than that of
glass, there is not a well established process like chemical
strengthening to provide significant strength improvements after
mechanical shaping. Failures in sapphire are typically driven by
propagations of surface flaws under stress. Therefore, to improve
the strength and robustness of sapphire, it may be useful to apply
an ion implantation process to provide a strength enhancement.
[0035] The chemical strengthening process for glass, where
diffusion substitutionally replaces smaller ions with larger ions,
creates a compressive stress layer around the surface of the glass
part that serves to prevent the propagation of surface cracks. In
contrast, the instant ion implantation of sapphire bombards the
sapphire part with high energy ions which are embedded
interstitially or otherwise in the subsurface to create a similar
thin layer or compressive stress that serves to arrest crack
propagation. The sapphire ion implantation process results in a
strained lattice to depths generally less than approximately 1
micrometer. The strengthening is achieved utilizing ions of
nitrogen or argon, though this is not restrictive as a
concentration of any ions could create the lattice strain necessary
to have surface compressive stress.
[0036] The concentrations for strengthening may fall between
approximately 10.sup.13 and approximately 10.sup.19 ions/cm.sup.2.
Other concentrations outside this range may also be implemented,
however, care should be taken where low concentrations would not
create enough lattice distortion to have a measurable strength
effect and the high concentrations could cause surface degradation
as the implanted ions may rupture the surface, thereby reducing the
strength, or could create a structural change from crystalline to
amorphous that could degrade the strength. The choice of ion and
concentration may depend on the size of the ion, its energy, its
charge, and its chemical interaction with sapphire, as these will
determine the depth of the implanted layer, the amount of stress
created at the surface and the resulting color of the sapphire, if
any.
[0037] As impurities within sapphire can impart color, the specific
application may dictate whether a colored or colorless appearance
would be desired. Additionally, since ion implantation may be a
line of sight process, masks could be used to shield different
locations of the part for a desired effect. For example, perhaps
the concentrations required to achieve the maximum strengthening
lead to a color tint. In that case, ions could be chosen to create
a more desired color in specific locations while minimizing the
color tint in other areas. One plausible implementation of this
concept is implanting high concentrations of ions around the
exterior of a sapphire display to create a mask of a specific color
(like iron and titanium which may create a dark color, such as
black). Hence, the ion implantation may both improve strength in
the vulnerable edges and also provide a desired color. A reduced
concentration of potentially different ions may then be implanted
over the display section to also provide strengthening but avoid
coloring that would degrade the appearance of the display. This
technique would enjoy the additional benefit of creating a mask
that would appear within the sapphire rather than underneath as is
the case with conventional ink back printing.
[0038] In some embodiments, the equipment available for the
implantation process may influence both the depth of implantation
and techniques implemented. For example, if an implanting device
operates at or near 80 kilo-electron volts (keV), ions may be
implanted at a first depth, whereas an implanting device operating
at or near 160 keV may implant ions at a second depth which is
deeper than the first depth. Hence, the use of different implant
energies may provide for different stress profiles and protect
against different types and/or depth of damage. In some
embodiments, two (or more) implanting devices may be used to
implant ions at two different depths. Plasma processes may also be
utilized, in which the ions have different (e.g., lower) energy,
and implantation occurs at other depths (e.g., at lesser depth,
with respect to the implantation surface). Further, in some
embodiments, a single implanting device may be configured to
operate at two or more different energy levels to achieve a desired
stress profile.
[0039] Additionally, during the implanting process, the atoms of
the crystalline structure may be displaced. Specifically, as Ar, N,
Ti, Fe, or other ions bombard the surface of the crystal, the
Aluminum or Oxygen atoms may be displaced. To help preserve the
integrity of the crystalline structure, Al or O ions may be
reinserted through an ion implanting process subsequent to the
initial implanting steps. For example, Argon may initially be
implanted to achieve a desired strengthening profile and a
subsequent implantation step may be performed to reinsert any
Oxygen atoms that were displaced during the Argon implantation. One
or more of the implanting steps may also be performed at an
elevated temperature (e.g., between approximately 500 and 1800
degrees Celsius in some embodiments). For example, the Argon
implanting step may be performed at an elevated temperature
relative to the Oxygen step or vice-versa.
[0040] FIG. 1 illustrates an example sapphire part 100. The
sapphire part 100 may be formed through any suitable process
including, but not limited to, edge-defined film-fed growth (EFG),
Kyropoulos, Verneuil, Czochralski, flux, hydrothermal, vertical
horizontal gradient freezing ("VHGF"), and Bridgman (i.e.,
horizontal moving growth) processes. The sapphire part 100 may be
cut from a sapphire wafer, a sapphire ribbon or other such sapphire
member. The sapphire part 100 may take any suitable geometric shape
and may be created for any suitable purpose. In one embodiment, for
example, the sapphire part 100 may be generally have a rectangular
shape and may be configured to serve as a cover glass in an
electronic device. In other embodiments, the sapphire part 100 may
have a circular shape and may be configured to serve as a cover
glass for a camera.
[0041] One or more surfaces of the sapphire part 100 may be
implanted with ions to help strengthen the part. Specifically, for
example, a top surface 102 may be implanted with ions, as well as
one or more edges 104. In some embodiments, a surface, such as the
top surface 102 may have an implanted ion concentration gradient
with regions having different concentrations of ions and/or
different types of ions. For example, peripheral edge 106 of the
top surface 102 may have a higher concentration of ions than the
center 108 of the top surface. Additionally, or alternatively, the
top surface 102 may be implanted with a different concentration of
ions than the edges 104. Further, each of the edges 104 may have a
different concentration of ions.
[0042] Additionally, or alternatively, the peripheral edge 106 of
the top surface 102 may be implanted with different ions from the
center 108. For example, the peripheral edge may be implanted with
titanium ions and/or iron ions, while the center 108 may be
implanted with nitrogen and/or argon ions.
[0043] It should be appreciated that other ions and/or other
combinations of ions may be implemented. The edges 104 may also be
implanted with different ions from those of the top surface 102
and/or one or more of the edges may be implanted with different
ions from another edge. Further, the top surface and a bottom
surface may have both different ion concentrations and/or different
implanted ions.
[0044] FIG. 2A illustrates an ion implantation system 110 for
implanting ions into the sapphire part 100. Generally, the
implantation system 110 may operate according to conventional
techniques. Initially, the multiple parts 100 may be positioned in
an end station 112 so that ions may be directed at and implanted in
the part 100. The ions for implantation start at an ion source 114
with magnets 115. The ion source 114 includes a chamber 116 (or
anode) and a filament (or cathode) 118. Magnets 115 are located
about the ion source 114. An element such as titanium, argon, iron,
nitrogen, or another element may be fed into the chamber 116 via an
element source 120 and converted into a plasma. The element is
passed through an ion extraction member/pre-acceleration unit 122
before a being redirected by a magnet 124 and filtered or separated
by a mass analyzing slit 125. The ions are subsequently passed
through an ion acceleration column 126. The ions are passed through
magnetic quadrupole lenses 128 and an electronic scanning system or
unit 130 before impacting the part.
[0045] FIG. 2B illustrates an alternate ion implantation system 110
for implanting ions into the sapphire part 100, via a plasma ion
immersion process. In the particular configuration of FIG. 2B, for
example, the implantation system 110 includes a vacuum chamber type
end station 112 for implanting ions into a selected surface of a
sapphire (crystalline aluminum oxide or AlOx) part or component
100, where the selected ions 131 are generated from an electron/ion
plasma 131A.
[0046] The implantation ions 131 are provided by plasma ion source
121, which is configured to generate an electron/ion plasma 131A
including the particular ions 131 that are selected for
implantation into sapphire part 100, for example aluminum, oxygen,
nitrogen argon, magnesium, titanium, copper, iron or chromium ions
131, or a combination thereof. Vacuum chamber end station 112 is
coupled to plasma source 121 via a vacuum conduit or other coupling
component 132. Vacuum chamber 112 may also include various vacuum
valves and pump components 133 and 134, in order to maintain a
desired low pressure suitable for performing plasma immersion ion
implantation processing of sapphire part 100.
[0047] As shown in FIG. 2B, a cover glass or other sapphire part
100 is immersed or exposed to the plasma 131A, for example using a
fixture or support member 135, so that the surface 101 selected for
ion implantation is exposed to the selected ions 131. An electrode
136 is provided in contact or charge communication with the part
100, for applying a voltage to separate the selected ions 131 from
the electron/ion plasma 131A, and to accelerate the ions 131 toward
the selected surface 101.
[0048] A power supply 137 is provided to generate a selected
implantation voltage on the electrode 136, for example a negative
operating voltage -V.sub.0 on the order of a few kilovolts (kV) in
absolute value (e.g., about 1 kV to about 10 kV), or on the order
of tens or hundreds of kilovolts (e.g., about 10 kV to about 100
kV, or more), so that the selected ions 131 are accelerated toward
the implantation surface 101 of the sapphire part 100. In
accelerating toward implantation surface 101, the ions 131 gain a
kinetic energy of K=qV.sub.0, where q is the absolute value of the
ionic charge, for example e, 2e, 3e, etc., and in which e is
absolute value of the fundamental charge on the electron.
[0049] Thus, the energy qV.sub.0 represents an ion implantation
energy, which can be selected by choosing the operating voltage
V.sub.0 and the ionization charge q (or the ionization level) to
implant the ions 131 at a desired target depth (or in a desired
target depth range) within the sapphire part 100. The implantation
depth is defined with respect to the selected implantation surface
101, so that the selected ions 131 are implanted at the target
depth beneath the implantation surface 101 of the sapphire part
100, or within the corresponding target depth range. The
implantation depth also depends upon the size of the selected ions
131 and the corresponding cross section for scattering from the
atoms in the crystal lattice of sapphire part 100, as well as the
ionization order or charge q.
[0050] For example, the power supply 137 may operate in a pulsed DC
mode, where the operating voltage -V.sub.0 is imposed on the
electrode 136 (and the sapphire part 100) for a relatively short
time, as defined by the plasma frequency of the electron/ion plasma
131A, for example on the order of a few microseconds or more (e.g.,
about 1 .mu.s or less to about 10 .mu.s or more). During the DC
pulse, the electrons in the electron/ion plasma 131A are repelled
away from the selected ion implantation surface 101, due to the
negative charge pulse -V.sub.0 imposed on the sapphire part 100 by
the electrode 136.
[0051] At the same time, the selected ions 131 are accelerated
toward the sapphire part 100, and are implanted at the desired
target depth or range beneath the selected ion implantation surface
101, based on the implantation energy, charge, and scattering cross
sections, as described above. Alternatively, a substantially
constant DC voltage may be applied, over an implantation time of
substantially more than 1-10 .mu.s, for example on the order of
milliseconds, or on the order of seconds or more. The implantation
time may be determined, for example, depending on ion selection,
plasma density, charge number, and other parameters, as compared to
the desired ion surface density and target depth, and the resulting
compressive stress, color, transparency and opacity of the sapphire
part 100 proximate the selected ion implantation surface 101.
[0052] In some designs, the vacuum chamber end station 112 may also
include a heater 138 or other device configured to heat the
sapphire part 100, for example via a conductive path utilizing
fixture 135, or by heating the sapphire part 100 together with the
interior of vacuum chamber 112 via a combination of conduction,
radiation, and convection. In these designs, the sapphire part 100
may be heated to a sufficient diffusion temperature such that the
selected ions 131 diffuse to a greater depth than the target depth,
beneath the selected surface 101 of the sapphire part 100.
[0053] Heating may be conducted at low pressure within vacuum
chamber 112, or in an inert atmosphere at higher pressure. For
example, the sapphire part 100 may be heated to a diffusion
temperature of about 500.degree. C. to about 1800.degree. C., e.g.,
for a diffusion period of minutes or hours, so that the selected
ions 131 diffuse to a greater depth than the target depth, beneath
the selected ion implantation surface 101 of the sapphire part 100.
In general, the diffused ions will maintain a diffused
concentration sufficient to generate compressive stress in the
selected ion implantation surface 101 of the sapphire part 100, as
described above.
[0054] Additional ions 131 may also be embedded into the selected
surface 101, either before or after heating the sapphire part 100
to diffuse the selected ions 131 to greater depth, or during the
heating process. For example, the additional ions 131 may be
embedded at the original target depth (e.g., using the same
implantation energy or pulse voltage V.sub.0), or at another target
depth (e.g., using a different implantation energy or pulse voltage
V.sub.0). Similarly, the additional ions 131 may be generated from
the same element as the original ions 131, as embedded or implanted
into the selected surface 101 before heating the sapphire part 100
to the diffusion temperature. Alternatively, the plasma ion source
121 may be configured to generate the selected ions 131 from
different elements, for embedding into the selected surface 101
before, during or after heating the sapphire part 100 to the
diffusion temperature.
[0055] The power supply 137 may also be configured to generate the
operating voltage V.sub.0 with a gradient across the electrode 136,
such that the selected ions 131 are embedded into the selected
surface 101 of the sapphire part 100 at different depths or
concentrations, as defined along the voltage gradient, based on the
corresponding gradient in the implantation energy. For example,
electrode 136 may be provided in segmented form, as shown in FIG.
2B, with different voltages applied to different electrode
segments, in order to generate the desired voltage gradient across
the selected surface 101 of the sapphire part 100, and thus to
generate corresponding gradients in the implantation depth or
density of the implanted ions 131.
[0056] In additional examples, the sapphire part 100 may be masked,
for example by utilizing electrodes 136 as the masking structure,
or using a different masking material. In these applications, the
selected surface 101 is exposed to the ions 131 in the electron/ion
plasma 231, while at least one other surface of the sapphire part
100 is masked, so that the ions 131 are embedded into the selected
surface 101, and the ions 131 are not embedded into the other
(masked) surfaces of sapphire part 100, which are covered by
electrodes or other masking elements 136.
[0057] FIG. 3 illustrates a support member 140 of the end station
112 that supports the sapphire part 100. The support member 140 may
generally include two opposing structures 142 that pinch upon the
sapphire part 100 to secure the sapphire part. Due to the hardness
of the sapphire, there is generally little concern that the
opposing structures 142 will damage the sapphire part 100. However,
in some embodiments, a cushioning member or members may be provided
at the interface between structures 142 and the sapphire part 100.
The support member 140 may be configured to move and or rotate so
that multiple sides of the sapphire part 100 can be exposed to the
ions. As may be appreciated, there may also be multiple or many
support members in the end station, supporting multiple or many
sapphire parts.
[0058] FIGS. 4-7 are partial cross-sectional views of the sapphire
part 100, for example as taken along line IV-IV in FIG. 3. It
should be appreciated that the present drawings are not done to
scale and are intended to merely be illustrative of the concepts
set forth herein. As such, the drawings should not be read as
limiting or as expressing size, dimensions or exact relationships
of the illustrated items.
[0059] FIG. 4 shows a lattice crystalline structure 150 of the
sapphire part 100. As discussed above, in the present ion
implantation process, ions may be implanted into an interstitial
space 152 of the lattice crystalline structure 150. Alternatively,
the ions may replace existing atoms in the sapphire lattice or fill
vacant sites in the sapphire lattice, or the ions may be embedded
so as to make portions of the embedded region substantially
amorphous or non-crystalline in nature.
[0060] For example, ions may penetrate to a primary lattice layer
or site in lattice 150 and displace an existing (e.g., aluminum or
oxygen) atom, or occupy an empty site in primary lattice 150, so
that the implanted ions are disposed within the primary crystalline
structure of sapphire part 100. Alternatively, ions may penetrate
to and occupy interstitial sites 152, forming a secondary lattice
structure as shown in FIG. 5.
[0061] FIG. 5 shows ions 154 implanted into the sapphire part 100,
for example into the interstitial space 152. The implantation of
ions 154 into interstitial spaces 152 (or otherwise implanted into
the sapphire part 100) may create a compressive layer within the
sapphire structure that helps to prevent the propagation of cracks
or defects within the surface of the sapphire part 100.
[0062] For example, implanted ions 154 may occupy interstitial
sites 152 as shown in FIG. 4, forming a secondary lattice structure
or secondary lattice layer disposed within or between the primary
(e.g., sapphire) crystalline lattice of part 100, as shown in FIG.
5. Alternatively, implanted ions 154 may occupy sites in primary
lattice 150, as described above. Implanted ions 154 may also
generate local disruptions in the lattice structure, forming a
localized area of amorphous (non-crystalline) material in an
embedded ion region, within the surrounding primary lattice 150 of
sapphire part 100. The implanted ions may be +1 ions, +2 ions, or
of another ionic level.
[0063] FIG. 6 illustrates the compressive layer 160 and a crack 162
or defect in the surface 102. The compression provided by the
implanted ions 154 on the lattice crystalline structure prevents
the crack 162 from expanding. Thus, the implanted ions help to
preserve the integrity of the sapphire part, for example should a
defect or crack develop due to stresses such as drop events that
result in the sapphire part impacting a hard surface.
[0064] FIG. 7 shows both a top surface 102 and a bottom surface 103
of the sapphire part 100 having a compressive layer 160 created
through ion implantation. In some embodiments, the top surface 102
and/or a portion of the top surface may be implanted with different
ions and/or a different concentration of ions than the bottom
surface 103. It should be appreciated that in other embodiments,
one of the surfaces may not be implanted with ions. This may be the
case when one of the surfaces is not to be exposed externally from
a device housing, thus limiting its exposure to defect inducing
impacts and other operational effects.
[0065] The concentration of implanted ions may generally be between
approximately 10.sup.13 and approximately 10.sup.19 ions/cm.sup.2.
However, in some embodiments, the concentrations may be greater
than or less than that range.
[0066] FIG. 8 illustrates a graph 170 plotting strength versus ion
concentration in a sapphire part. Specifically, the horizontal axis
represents the concentration of implanted ions and the vertical
axis illustrates the strength of the sapphire structure. As shown
by the curve 172, as ions are implanted to certain concentrations,
the strength of the sapphire structure increases before beginning
to decrease after a threshold level of concentration has been
exceeded. For the purposes of illustration, a concentration of
about 10.sup.13 ions/cm.sup.2 may be at or near a first mark 174 on
the horizontal axis and a concentration of about 10.sup.19
ions/cm.sup.2 may be at or near a second mark 176. Generally, the
concentration of ions should be at a level that provides increased
strength. As the curve 172 shows, an excessive concentration may
decrease the strength of the sapphire.
[0067] Although much of the foregoing discussion is related to the
surfaces of the sapphire part 100, it should be appreciated that
the edges 104 of the sapphire part may also have ions implanted
therein and the foregoing applies to the edges 104 of the sapphire
part 100 as well. Specifically, the support member 140 of FIG. 3
may be configured to hold the sapphire part 100 in a manner that
allows the edges to be impacted by the ion stream, as shown in FIG.
9. The edges 104 may be implanted with the same or different ions
from the top and/or bottom surfaces 102, 103 and at the same or
different concentrations. The support member 140 may be configured
to rotate so that all edges 104 of the sapphire part 100 may be
exposed to ion implantation. Additionally, the support member 140
may be configured to move in different directions to accommodate an
edge shape. For example, the support member 140 may tilt so that
ions may more directly impact a straight or chamfered edge, or
other edge structure.
[0068] FIG. 10 illustrates a chamfered edge 180 of a sapphire
member. Additionally, a curve 182 on the chamfered edge illustrates
the relative concentration of ion implantation. As shown, the ions
may be more concentrated at or near a flat portion of the edge 180,
as it may receive the ion stream most directly. The slanted
portions of the edge 180 may have a lower concentration of ions. In
some embodiments, however, the concentration may be consistent
across all parts of the edge 180. For example, in embodiments where
the support member 140 is able to tilt, the slanted edges may be
directly impacted by the ion stream, and the ion concentration may
vary across the edge 180, or be substantially consistent or
substantially the same across the edge 180.
[0069] One of the limits of ion implantation may be the depth of
the treatment. Generally, ion implantation may be limited to a
maximum depth of approximately 1 micrometer, as defined with
respect to the implantation surface. As such, there is a risk that
either processing defects or handling damage could introduce
scratches or defects that penetrate the surface of the material
deeper than the treated layer and, therefore, limit its
effectiveness in preventing crack propagation. To improve the
process, ion implantation could be completed serially with high
temperature heat treatments being completed in between each
implantation step, or between one or more consecutive implantation
steps.
[0070] In these embodiments, an implantation may be completed which
would lead to lattice strain to a depth of x. By treating the
material at high temperature, diffusion would allow the implanted
ions to diffuse deeper into the material to x+y, while decreasing
the ion concentration at the surface. Then another implantation
step could be completed to again raise the ion concentration level
at the surface. These steps may be completed repeatedly to yield a
final treated layer with the same level of surface stress of a
regular single treatment, but with a greater ion penetration depth
than would have been otherwise possible.
[0071] FIG. 11 illustrates ions diffusing into deeper lattice
layers through a heating step. A heat source 190 may be provided to
heat the surface 102 or to heat the sapphire part 100. As the
sapphire part is heated, lattice structure 150 may be relaxed and
the ions 154 may diffuse into deeper layers of the lattice
structure. In some embodiments, the end station 112 or vacuum
chamber (FIG. 2A or FIG. 2B) may serve as an oven or may otherwise
be heated so that the sapphire part 100 is not moved between the
heating and implanting steps. In other embodiments, multiple
batches of sapphire parts may be staggered and alternate between
heating and ion implantation steps, so that as one batch is in the
end station 112, another batch may be heated, for example in an
oven outside of the end station 112, or in an end station oven
112.
[0072] Diffusion may reduce the concentration of ions in the outer
layer, proximate or adjacent the implantation surface. As such, a
subsequent ion implantation step may be utilized to replenish the
ions in the outer layer, as shown in FIG. 12. Through the
combination of implantation and heating steps, ions may be
implanted deeper into the lattice structure to help prevent against
defect propagation at layers beneath the surface.
[0073] In some embodiments, multiple heaters and/or multiple ion
implantation systems may be implemented. In one embodiment, a first
ion implanter may implant ions of a first element and second ion
implanter may implant ions of a second element to achieve a desired
effect. In between each ion implantation step, or between two or
more consecutive ion implantation steps, a heater may be used to
help diffuse the previously implanted ions.
[0074] FIG. 13 illustrates the part 100 after ion implantation,
where a first zone 200 of the top surface 102 is colored (e.g.,
blackened or given another color) by the implanted ions and a
second zone 202 remains substantially clear or transparent.
Generally, the first zone 200 may include a peripheral portion of
the top surface 102 and the second zone 202 may include the central
portion of the top surface. In some embodiments, masks may be used
during the ion implantation process to create the different (e.g.,
clear and colored) zones.
[0075] From a process perspective, ion implantation may be
performed after post-processing annealing and prior to decoration
as the implantation may damage or affect any surface inks or
coatings, and could be expected to be most successful on a surface
with minimized defects. FIG. 14 is a method 210 of processing a
sapphire part in accordance with an embodiment of this
disclosure.
[0076] Initially, a sapphire crystal is grown (Block 212). The
sapphire crystal may then be cut (Block 214) to shape the sapphire
part, which is then passed through an annealing process (Block
216). One or more surfaces of the sapphire part may then be
bombarded with ions of an ion stream for ion implantation (Block
218). During ion implantation, the sapphire part position may be
manipulated relative to the ion stream in order to properly implant
ions into each surface desired. Additionally, certain regions of
the sapphire part may be masked during one or more ion implantation
steps to achieve a desired concentration, and/or a desired ion
selected for implantation into certain regions and not others. The
sapphire part may then be heated to cause diffusion of the ions
into deeper lattice layers (Block 220).
[0077] After heating, the sapphire part may again be bombarded with
ions (Block 222). The ion implantation, manipulation, masking, and
heating/diffusion steps may be repeated in any order, number or
combination, in order to achieve desired ion selection,
implantation depth, concentration, color, and other properties.
[0078] Subsequently, post-processing steps such as ink mask
application may be performed (Block 224). Typically, there would
not likely be a polishing step after ion implantation, in order to
preserve compressive stress and other desired properties.
Alternatively, a light polish step or other post-implantation
surfacing process may be applied, after ion implantation into the
surface.
[0079] Other techniques may be implemented to implant ions into the
sapphire lattice structure, interstitially or otherwise. For
example, in some embodiments the sapphire member may be coated with
an ionic slurry or paste and an electrical current may be applied
to the slurry, in order to embed selected ions in selected surface,
to a selected depth. Alternatively, a plasma immersion process may
be utilized, as described above, either alone or in any combination
with ion beam deposition, ionic slurry, and other ion deposition
methods.
[0080] FIG. 15 illustrates an ionic slurry process. In particular,
a sapphire member 230 is shown with an ion paste 232 coating on one
or both (or each) side 102, 103 of the sapphire member 230.
Electrical terminals 234 (e.g., singular, unitary or unique
terminals having opposite voltages .+-.V.sub.0) are electrically
coupled to the ion paste 232 or sapphire member 230, and an
electrical current .+-.I.sub.0 is applied to the ion paste through
the terminals 234, for example using a current supply or power
supply 238.
[0081] Specifically, the terminals 234 may apply opposite charges
or voltages .+-.V.sub.0 on the different (e.g., major opposing)
sides 102, 103 of the sapphire member 230, so that ions flow across
the selected implantation surface (e.g., the top or bottom surface
102 or 103). The charge or bias voltage of the terminals 234 may be
somewhat lower than in ion beam and plasma deposition processes,
and also may be alternated, so that ions in ion paste 232 are
implanted into each side 102 and 103 of the sapphire part or member
230, or into the edges of the sapphire member 230, or into a
combination of the sides 102, 103 and edges 104 of the sapphire
member 230. That is, the cathode and anode may be switched (or one
grounded terminal 234 and another terminal 234 with voltage
.+-.V.sub.0 may be used), to provide an alternating current (AC) or
direct current (DC) bias for implanting ions in ionic paste or
slurry 232 to selected sides 102, 103 and/or edges 104 of the
sapphire member 230.
[0082] FIG. 16 illustrates the biasing of the terminals 234 to
cause (e.g., positive) ion flow in the direction of the arrow 236.
Any suitable power supply 238 may be used to apply the electrical
current .+-.I.sub.0 to the ion paste 232. For example, in some
embodiments, an alternating current (AC) .+-.I.sub.0 may be applied
to the ion paste 232 to implant the ions. In other embodiments, a
direct current (DC) .+-.I.sub.0 may be applied to the ion paste
232, and periodically the polarity of the terminals 234 may be
switched. In still other embodiments, one or more switched
capacitors may be included in power supply 238, and used to provide
impulse charges to the terminals 234.
[0083] Generally, diffusion into the sapphire member 230 may be
faster than diffusion out of the sapphire member, so that upon
completion of the process there are ions implanted into the
sapphire, for example interstitially or by substitution into the
crystal lattice. Alternatively, ions may occupy empty lattice
sizes, or form a region of substantially amorphous structure,
within the crystal lattice. The ion paste 232 may include at least
one ionic element and a suitable medium (or suitable media) for the
selected ionic element. The selected ions or ionic elements may
have size and chemistry generally the same as or similar to that of
ions in the magnetic quadrupole lens and plasma immersion systems,
as described above.
[0084] It should be appreciated that the ion implantation system
illustrated in FIGS. 15 and 16 may also be implemented together
with the above-described heating steps to help the ions further
diffuse into the lattice crystalline structure of the sapphire. In
some embodiments, the heat may be applied while the ion paste 232
is still on the surface of the sapphire member 230, while in other
embodiments the ion paste may be removed prior to the heating step.
In still other embodiments, the ion implantation process may be
conducted in a furnace or an oven such as a vacuum furnace end
station or finishing chamber 112, so that the heating and ion
implanting steps may be performed without moving the sapphire
member.
[0085] In some embodiments, the depth of implantation of the ions
may be a function of the implantation energy, the size of the ion
and the crystal plane into which the ions are implanted. The
implantation energy may be a function of the systems, machines and
methods used to implant the ions. An ion implantation device, such
as illustrated in FIGS. 2A, 2B, 15 and 16, may operate at a
particular energy level that is determinative, in part, of the
depth of implantation of the ions. For example, the implantation
device may operate at 80 keV, which may correlate to a first
implantation depth, whereas a second implantation device may
operate at 160 keV and may correlate to a second implantation depth
which is deeper than the first implantation depth. Alternatively,
the ion charge may also be selected to target a particular
implantation depth, for example with singly-ionized (+1 charge)
atoms of a particular type penetrating to a first target depth, and
double or multiply-ionized (+2 charge or higher) atoms of the
particular type penetrating to a second, lesser target implantation
depth, as defined with respect to the implantation surface.
[0086] More generally, different ion beam, plasma, and ionic
slurry-based ion implantation systems and methods may be used,
either alone or in combination, in order to implant selected ions
at different ion densities and implantation depths, based on
parameters including, but not limited to, ion type (atomic number
and atomic mass), charge (ionization level), implantation energy,
and angle of incidence. The different implantation depths and ion
types and densities generally create different compressive or
tensile stresses at different depths of the crystalline structure,
and may be selected so as to be operable to prevent propagation of
damage at different levels or depths in the structure, as defined
with respect to the ion implantation surface.
[0087] Turning to FIG. 17, an implantation curve 240 is illustrated
which shows the compressive stress at different depths of a
crystalline structure due to ion implantation. The horizontal axis
241 represents depth in the crystalline structure and the vertical
axis 243 represents (e.g., compressive) stress. For example, a
first stress peak 242 may be located at a first depth and a second
stress peak 244 may be located at a second depth, different from
the first depth. Thus, one, two or more distinct depths may be
subject to the same or different compressive stresses, based on the
selected ion implantation systems and methods, in order to prevent
propagation of cracks in the crystalline structure.
[0088] Thus, the ions may be implanted with a concentration
gradient, such that the ion concentration varies as a function of
depth in the sapphire material, as defined in a substantially
transverse or orthogonal (perpendicular) sense with respect to the
implantation surface. Alternatively, ions may be implanted with a
concentration gradient across the implantation surface, so that the
ion concentration varies in a lateral direction along the surface,
for example with different selected ion concentrations and/or
implantation depths along the peripheral edge, as compared to the
center portion or region, e.g., as described above with respect to
FIG. 1.
[0089] The different stress peaks and depths may be selected or
targeted based on common damage profiles. For example, a first
stress peak may be placed approximately at a depth at which
superficial damage commonly occurs. For example, the first peak 242
may be approximately centered at a depth of about 20 nm or less,
with respect to the ion implantation surface. The second peak 244
may be located at depths that target damage deeper than that of a
superficial nature, for example at a depth greater than
approximately 20 nm.
[0090] As may be appreciated, ion implantation at different depths
may be performed by one or more implanters or implantation systems.
For example, a first implanter may operate at energy levels that
implant ions at a deeper level than a second implanter that may
operate at lower energy levels, or vice-versa. For example, a first
implanter may operate at approximately 160 keV and a second
implanter may operate at approximate 80 keV. Different ion beam,
plasma immersion, and ionic slurry implantation systems and methods
may also be utilized, as described above.
[0091] Further, in some embodiments, a single implanter may be
configured to operate at multiple different energy levels or using
different methods, in order to achieve the desired implantation
profile. The energy level of the implanter may also be configured
to switch between different operating energy levels in subsequent
ion implantation steps. Further, the implanter may be configured to
continuously implant ions as it transitions between different
energy levels. Thus, ions may be implanted in or at one or more
substantially discrete levels or depths within the crystalline
structure, or at other than generally discrete levels, for example
in a substantially continuous range of depths in the crystalline
structure.
[0092] FIG. 18 illustrates the implantation curve 240 with profile
smoothing. Specifically, ions may be implanted at depths 246 in
between the two peaks 242 and 244. The smoothing may help
strengthen layers of the structure in between the targeted depths.
The profile smoothing may occur as a result of the continuous
implantation of the implanter as it transitions between different
targeted energy levels. Additionally, or alternatively, profile
smoothing may occur due to diffusion of the ions, for example
during a diffusive heating step or annealing step. Moreover,
smoothing may occur as a result of an overlap of ion implantation
depths for two or more discrete implantation steps using different
energy levels. That is, each step of implantation may include ions
that do not implant at the precise target depth, thereby resulting
in an implantation curve that may overlap with ion implantations
intended for a different target depth.
[0093] FIG. 19 illustrates an implantation curve 248 that may
represent a net stress curve that results from the curve smoothing.
As illustrated, the implantation curve 248 includes increased
compressive stress at two peaks, which may represent target depths.
However, there is compressive stress that extends from the surface
(e.g., the origin on the horizontal axis) to beyond the deeper of
the two peaks (e.g., beyond the second target depth).
[0094] It should be appreciated that the net stress curve may be
customized based on desired strength characteristics for the
structure. That is, the specific target depths may be selected for
increased compressive stress to provide a desired protection
against specific types of damage. Additionally, it should be
appreciated that more or fewer than two depths may be targeted for
the ion implantation. Moreover, the depths may be varied based on
using different ions or elements to control the depth of
implantation rather than the implantation energy, or some
combination of energy level, implantation method, and/or
ion/element selection. Further, the implanted ion density may vary
at the different depth levels. As such, a first depth may include a
first ion having a first concentration and a second depth may
include a second ion having a second concentration different from,
or the same as, the concentration of the first ion at the first
depth.
[0095] Further still, in some embodiments, there may be some
combination of ions at a particular depth level to achieve a
desired effect. For example, titanium ions and argon ions may be
implanted at the same or approximately same level. The desired
effect may include a desired colorization and/or strengthening due
to the implanted ions. In some embodiments, a particular depth
level may be selected for strengthening and another level may be
targeted to give a particular colorization.
[0096] In some embodiments, the depth levels of ion implantation
may vary based on which surface of the crystalline structure is
being implanted. For example, a top surface of the structure may
have different ion implantation depths than those of the sidewalls
of the structure. Additionally, a top surface may have different
ion implantation depths from that of a bottom or sidewall surface,
and/or different ion concentrations and so on. Different
ions/elements or combinations thereof may also be implanted in
different surfaces of the structure.
[0097] In some cases, the bombardment of ions into the crystalline
structure (or other ion implantation process) may cause
displacement of the atoms that make up the structure. That is, as
ions are implanted into the structure, e.g., to either strengthen
or add color to the structure, aluminum or oxygen atoms may be
displaced from the crystal lattice. It is believed that the
displacement may be generally more prevalent at the surface layers
of the structure. In some cases, either aluminum or oxygen atoms
may also have a higher rate of displacement, relative to the other
atom. For example, more oxygen may be displaced than aluminum.
[0098] As may be appreciated, displacement may change the chemical
makeup of the structure. To preserve the integrity of the
structure, oxygen and/or aluminum atoms may be provided to replace
displaced atoms. For example, if oxygen atoms are displaced at a
higher rate than aluminum, oxygen atoms or ions may be bombarded
onto the surface of the structure. In some embodiments, both oxygen
and aluminum (or other selected atoms or ions) may be bombarded
onto the surface, in the same or different atom bombardment or
implantation steps, for example via an ion beam process, or
utilizing a plasma immersion or ionic slurry process, or a
combination of such processes, as described above, or via another
atomic or ionic bombardment process.
[0099] FIG. 20 is a flow chart illustrating an example process 250
that include the atom bombardment step. Initially, doping ions may
be implanted (Block 252) in accordance with the techniques
discussed above. A heating diffusion step (Block 254) may be
performed to help the ions to diffuse into different layers of the
structure. A second ion implantation step (or additional
implantation steps) may then be performed (Block 256). The second
ion implantation step may be performed with a different
implantation energy, with a different concentration level, a
different ion, or at a different temperature, or with the same
operational parameters as the first implantation.
[0100] After the ion implantation steps, the surface may be
bombarded with aluminum and/or oxygen atoms (Block 258). This step
may be performed at a higher or lower temperature from that of the
implantation steps. Additionally, one or more annealing steps 260
may be performed (Block 260). The annealing steps may help restore
the crystalline structure (e.g., achieve a proper or desired
relationship/ratio of aluminum atoms to oxygen atoms).
[0101] The various techniques described herein have numerous
different applications. In particular, in consumer electronic
devices, there may be applications related to and including, but
not limited to, device cover glasses, windows, and other structures
within the devices. One such exemplary use is for a camera window
or cover glass component, or a selected surface or portion
thereof.
[0102] FIG. 21 illustrates a camera window 280. One either side (or
surrounding) the camera window is a trim element 282 which is
provided to prevent cross-talk from a strobe element 284 (e.g., a
flash) and/or other light source, such as a display that may be
positioned within a housing relative to the camera window and back
plate 286. Turning to FIG. 22, in accordance with the present
techniques, a sapphire window 290 may replace or be utilized for
the camera window, and may have its edges 292 colored to
effectively prevent cross talk from the strobe 284 and other
sources, for example by ion implantation with selected ions of
sufficient density to render one or more edges 292 substantially
opaque. As such, the (e.g., separate or discrete) trim element 282
may be eliminated. This may provide several advantages such as
reduced z-stack dimensions (e.g., possibly thinner devices), as
well as stronger windows for the camera.
[0103] In processing the sapphire window component, top and bottom
surfaces may also be implanted with different ions and/or
concentrations relative to the edges so that the top and bottom
surfaces have limited or substantially no effect on the optics of
the window, as compared to a component without ion implanted
surfaces. That is, while the edges may be implanted with ions to be
substantially opaque or prevent light passage, the top and bottom
surfaces may be implanted with ions in concentrations that will
substantially maintain the transparency of the sapphire
material.
[0104] Although the foregoing discussion has presented specific
embodiments, persons skilled in the art will recognize that changes
may be made in form and detail without departing from the spirit
and scope of the disclosure. For example, the processing steps may
be performed in another order, or in different combinations.
Further, the different ion implantation steps may include different
charges (e.g., single charged and double charged ions) as well as
different implantation methods and energy levels. As such, the
implantation depths may be selected based on multiple different
parameters and their combinations. Accordingly, the specific
embodiments described herein should be understood as examples and
not limiting the scope of the disclosure.
[0105] The foregoing merely illustrates the principles of the
invention. Various modifications and alterations to the described
embodiments will be apparent to those skilled in the art, in view
of the teachings herein. It will thus be appreciated that those
having skill in the art will be able to devise numerous systems,
arrangements and methods which, although not explicitly shown or
described herein, embody the principles of the disclosure and are
thus within the spirit and scope of the present invention. From the
above description and drawings, it will be understood by those of
ordinary skill in the art that the particular embodiments shown and
described are for purposes of illustration only, and references to
details of particular embodiments are not intended to limit the
scope of the present invention, as defined by the appended
claims.
* * * * *